Fixed #28991 -- Added EmptyFieldListFilter class in admin.filters.

Thanks Simon Charette and Carlton Gibson for reviews.

Co-Authored-By: Jonas Haag <jonas@lophus.org>
Co-Authored-By: Christophe Baldy <christophe.baldy@polyconseil.fr>

1 files changed, 102 insertions, 2 deletions

diff --git a/tests/admin_filters/tests.py b/tests/admin_filters/tests.py
index 6db2147e51..75769085e0 100644
--- a/tests/admin_filters/tests.py
+++ b/tests/admin_filters/tests.py
@@ -3,8 +3,8 @@ import sys
 import unittest
 
 from django.contrib.admin import (
-    AllValuesFieldListFilter, BooleanFieldListFilter, ModelAdmin,
-    RelatedOnlyFieldListFilter, SimpleListFilter, site,
+    AllValuesFieldListFilter, BooleanFieldListFilter, EmptyFieldListFilter,
+    ModelAdmin, RelatedOnlyFieldListFilter, SimpleListFilter, site,
 )
 from django.contrib.admin.options import IncorrectLookupParameters
 from django.contrib.auth.admin import UserAdmin
@@ -248,6 +248,17 @@ class BookmarkAdminGenericRelation(ModelAdmin):
     list_filter = ['tags__tag']
 
 
+class BookAdminWithEmptyFieldListFilter(ModelAdmin):
+    list_filter = [
+        ('author', EmptyFieldListFilter),
+        ('title', EmptyFieldListFilter),
+    ]
+
+
+class DepartmentAdminWithEmptyFieldListFilter(ModelAdmin):
+    list_filter = [('description', EmptyFieldListFilter)]
+
+
 class ListFiltersTests(TestCase):
     request_factory = RequestFactory()
 
@@ -1374,3 +1385,92 @@ class ListFiltersTests(TestCase):
         changelist = modeladmin.get_changelist_instance(request)
         changelist.get_results(request)
         self.assertEqual(changelist.full_result_count, 4)
+
+    def test_emptylistfieldfilter(self):
+        empty_description = Department.objects.create(code='EMPT', description='')
+        none_description = Department.objects.create(code='NONE', description=None)
+        empty_title = Book.objects.create(title='', author=self.alfred)
+
+        department_admin = DepartmentAdminWithEmptyFieldListFilter(Department, site)
+        book_admin = BookAdminWithEmptyFieldListFilter(Book, site)
+
+        tests = [
+            # Allows nulls and empty strings.
+            (
+                department_admin,
+                {'description__isempty': '1'},
+                [empty_description, none_description],
+            ),
+            (
+                department_admin,
+                {'description__isempty': '0'},
+                [self.dev, self.design],
+            ),
+            # Allows nulls.
+            (book_admin, {'author__isempty': '1'}, [self.guitar_book]),
+            (
+                book_admin,
+                {'author__isempty': '0'},
+                [self.django_book, self.bio_book, self.djangonaut_book, empty_title],
+            ),
+            # Allows empty strings.
+            (book_admin, {'title__isempty': '1'}, [empty_title]),
+            (
+                book_admin,
+                {'title__isempty': '0'},
+                [self.django_book, self.bio_book, self.djangonaut_book, self.guitar_book],
+            ),
+        ]
+        for modeladmin, query_string, expected_result in tests:
+            with self.subTest(
+                modeladmin=modeladmin.__class__.__name__,
+                query_string=query_string,
+            ):
+                request = self.request_factory.get('/', query_string)
+                request.user = self.alfred
+                changelist = modeladmin.get_changelist_instance(request)
+                queryset = changelist.get_queryset(request)
+                self.assertCountEqual(queryset, expected_result)
+
+    def test_emptylistfieldfilter_choices(self):
+        modeladmin = BookAdminWithEmptyFieldListFilter(Book, site)
+        request = self.request_factory.get('/')
+        request.user = self.alfred
+        changelist = modeladmin.get_changelist_instance(request)
+        filterspec = changelist.get_filters(request)[0][0]
+        self.assertEqual(filterspec.title, 'Verbose Author')
+        choices = list(filterspec.choices(changelist))
+        self.assertEqual(len(choices), 3)
+
+        self.assertEqual(choices[0]['display'], 'All')
+        self.assertIs(choices[0]['selected'], True)
+        self.assertEqual(choices[0]['query_string'], '?')
+
+        self.assertEqual(choices[1]['display'], 'Empty')
+        self.assertIs(choices[1]['selected'], False)
+        self.assertEqual(choices[1]['query_string'], '?author__isempty=1')
+
+        self.assertEqual(choices[2]['display'], 'Not empty')
+        self.assertIs(choices[2]['selected'], False)
+        self.assertEqual(choices[2]['query_string'], '?author__isempty=0')
+
+    def test_emptylistfieldfilter_non_empty_field(self):
+        class EmployeeAdminWithEmptyFieldListFilter(ModelAdmin):
+            list_filter = [('department', EmptyFieldListFilter)]
+
+        modeladmin = EmployeeAdminWithEmptyFieldListFilter(Employee, site)
+        request = self.request_factory.get('/')
+        request.user = self.alfred
+        msg = (
+            "The list filter 'EmptyFieldListFilter' cannot be used with field "
+            "'department' which doesn't allow empty strings and nulls."
+        )
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
+            modeladmin.get_changelist_instance(request)
+
+    def test_emptylistfieldfilter_invalid_lookup_parameters(self):
+        modeladmin = BookAdminWithEmptyFieldListFilter(Book, site)
+        request = self.request_factory.get('/', {'author__isempty': 42})
+        request.user = self.alfred
+        with self.assertRaises(IncorrectLookupParameters):
+            modeladmin.get_changelist_instance(request)